For movies, look up what Alexa Mini's can do. The very recent past dominant Mini had a 3424x2202 resolution. Most movies shot digitally (most in the last like 20 years) were shot at below 4k. Many had special effects done at 1080p. When movie theaters switched to digital projection, most used 2048x1080 projectors and the shift towards 4k projectors wasn't that long ago.
The Alexa Mini LF can do 4448x3096. The Sony Venice 8k camera is a few years old only. There's a huge amount of loyalty to Arri, particularly the lenses. Panasonic and Z-Cam have 8k cameras. But like Arri, I'd bet most filmmakers would choose the 4k/6k cameras
Even the ones that opt for the 8k cameras, there very likely would be lower resolution cameras in use as well like the Alexa Mini or a 4k/6k Z-Cam or like a Sony FX3. Including most nature documentaries. Unless it's just wide canvases, you're not going to be mounting the 8k cinema cameras all over the place like you would cheaper small cameras like an FX3. Plus stuff like shooting at 240fps 12bit color for slow motion playback. I'm betting that none of the cinema cameras support that at 8k. So back down to probably 1080p. Don't know the status of 4k240 out there. That's a lot of bandwidth, storage, processing power, and cooling needed
Then there's 70mm filming. The vast majority of productions cannot do that. There's a lot of unused footage that goes into filmmaking. If you look at the size of a roll of 70mm film used for projecting a feature length film, it's huge. It's boutique equipment. There's not a ton of cinema 70mm cameras and lenses to rent. Camera operators. Labs to get them scanned for digital editing. 70mm will always be limited in adoption especially now that digital is the dominant form of cinematography
So 8k will for many many years be the land of upscaling and for native, old video games. Videos, I guess two 8k60 cameras rigged together for VR will lead the way along with an occasional movie/documentary. No guarantees that the movie theater will show it in 8k though. It's taken a very long time for 4k projection to approach standard for theaters in places like the US let alone poorer countries or countries with less mega theater chains that could more comfortably afford the upgrade